a2e9ab362b
Adds support to asyncio.gather() for the case that one or more (or all) sub-tasks finish and/or raise an exception before the gather starts. Signed-off-by: Damien George <damien@micropython.org>
66 lines
2.0 KiB
Python
66 lines
2.0 KiB
Python
# Test asyncio.gather() when a task is already finished before the gather starts.
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try:
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import asyncio
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except ImportError:
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print("SKIP")
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raise SystemExit
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# CPython and MicroPython differ in when they signal (and print) that a task raised an
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# uncaught exception. So define an empty custom_handler() to suppress this output.
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def custom_handler(loop, context):
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pass
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async def task_that_finishes_early(id, event, fail):
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print("task_that_finishes_early", id)
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event.set()
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if fail:
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raise ValueError("intentional exception", id)
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async def task_that_runs():
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for i in range(5):
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print("task_that_runs", i)
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await asyncio.sleep(0)
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async def main(start_task_that_runs, task_fail, return_exceptions):
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print("== start", start_task_that_runs, task_fail, return_exceptions)
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# Set exception handler to suppress exception output.
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loop = asyncio.get_event_loop()
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loop.set_exception_handler(custom_handler)
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# Create tasks.
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event_a = asyncio.Event()
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event_b = asyncio.Event()
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tasks = []
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if start_task_that_runs:
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tasks.append(asyncio.create_task(task_that_runs()))
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tasks.append(asyncio.create_task(task_that_finishes_early("a", event_a, task_fail)))
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tasks.append(asyncio.create_task(task_that_finishes_early("b", event_b, task_fail)))
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# Make sure task_that_finishes_early() are both done, before calling gather().
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await event_a.wait()
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await event_b.wait()
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# Gather the tasks.
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try:
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result = "complete", await asyncio.gather(*tasks, return_exceptions=return_exceptions)
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except Exception as er:
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result = "exception", er, start_task_that_runs and tasks[0].done()
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# Wait for the final task to finish (if it was started).
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if start_task_that_runs:
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await tasks[0]
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# Print results.
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print(result)
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# Run the test in the 8 different combinations of its arguments.
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for i in range(8):
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asyncio.run(main(bool(i & 4), bool(i & 2), bool(i & 1)))
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